Oil enters the Loop Current and is headed to the Florida Keys

Satellite imagery today from NASA's MODIS instrument confirms that a substantial tongue of oil has moved southeast from the Deepwater Horizon oil spill and entered the Gulf of Mexico's Loop Current. The Loop Current is an ocean current that transports warm Caribbean water through the Yucatan Channel between Cuba and Mexico. The current flows northward into the Gulf of Mexico, then loops southeastward just south of the Florida Keys (where it is called the Florida Current), and then along the west side of the western Bahamas. Here, the waters of the Loop Current flow northward along the U.S. coast and become the Gulf Stream. Once oil gets into the Loop Current, the 1 - 2 mph speed of the current should allow the oil to travel the 500 miles to the Florida Keys in 10 - 20 days. Portions of the Loop Current flow at speed up to 4 mph, so the transport could be just 4 - 5 days. It now appears likely that the first Florida beaches to see oil from the spill will be in the Lower Florida Keys, not in the Panhandle.

Figure 1. Satellite image of the oil spill taken at 12:40 EDT Monday May 17, 2010. The location of the Loop Current is superimposed. Image credit: University of Wisconsin and NASA.

Why is oil getting into the Loop Current?The winds over the oil spill location are offshore out of the northwest today, and offshore winds will continue intermittently through Wednesday, which should allow a substantial amount of oil to enter the Loop Current. The major reason oil is moving southwards is because of the instability of the currents in the Gulf of Mexico. The Loop Current is not a stable feature, and tends to surge northwards and southwards in a chaotic fashion, and in response to changes in the prevailing winds. Over the past week, chaotic behavior of the Loop Current and a clockwise-rotating eddy just to its north, just south of the oil spill location, have combined to bring a current of southward-moving surface water to the oil spill location. As strong on-shore winds from the southeast slackened this past weekend, oil has been drawn southward into the Loop Current. The latest NOAA trajectory forecasts failed to anticipate the movement of the oil into the Loop Current. The latest surface current forecasts from NOAA's HYCOM model show that oil could continue pouring into the Loop Current for most of the rest of the week. It is highly uncertain how diluted the oil might get on its voyage to northwestern Cuba and the Florida Keys this week, but the possibility for a major ecological disaster in the fragile Keys ecosystem cannot be ruled out. Southeast to east winds of 10 - 15 knots are expected to develop late this week and extend into early next week, which may be strong enough to impose a surface current that will shut off the flow of oil into the Loop Current by Friday or Saturday.

Figure 2. Forecast made at 8pm EDT Sunday May 16, 2010, of the Gulf of Mexico currents by NOAA's HYCOM model. A persistent southward flowing surface current is predicted to occur this week between the oil spill location (red dot) and the Loop Current. Image credit: NOAA.

Likely areas of impactBased on a study of 194 floating probes released into the Northeast Gulf of Mexico during a 1-year study in the 1990s (Figure 3), the west coast of Florida from Tampa Bay southwards to the Everglades is at minimal risk of receiving oil from surface currents. There is a "forbidden zone" off the southwest Florida coast where the shape of the coast, bottom configuration, and prevailing winds all act to create upwelling and surface currents that tend to take water away from the coast. This study implies that the greatest risk of land impacts by surface oil caught in the Loop Current is along the ocean side of the Florida Keys, and along the coast of Southeast Florida from Miami to West Palm Beach. Eddies breaking away from the Gulf Stream would also likely bring oil to northwest Cuba, the western Bahamas, and the U.S. East Coast as far north as Cape Hatteras, North Carolina, though at lesser concentrations. Southwest Florida cannot rest entirely, though--the "forbidden zone" is only true for surface waters, and there is onshore flow below the surface. Since recent ship measurements have detected substantial plumes of oil beneath the surface, southwest Florida might be at risk if one of these plumes gets entrained into the Loop Current. These subsurface plumes were also detected by current probes launched into the oil spill on May 8 by one of NOAA's hurricane hunter aircraft, according to one scientist I spoke to at last week's AMS hurricane conference. There are plans for the Hurricane Hunters to go out again tomorrow and drop more probes into the spill to attempt to get a better handle on where the oil is and where the currents are taking it.

Figure 3. Paths of 194 floating probes released into the yellow-outlined area in the northeast Gulf of Mexico between February 1996 and February 1997 as part of a study by the Mineral Management Service (MMS). The probes were all launched into waters with depth between 20 and 60 meters. Image credit: Yang, H., R.H. Weisberga, P.P. Niilerb, W. Sturgesc, and W. Johnson, 1999, Lagrangian circulation and forbidden zone on the West Florida Shelf, Continental Shelf Research Volume 19, Issue 9, July 1999, Pages 1221-1245 doi:10.1016/S0278-4343(99)00021-7

When will a Loop Current eddy break off?Every 6 - 11 months, the looped portion of the Loop Current cuts off into a clockwise-rotating ring of water that then slowly drifts west-southwest towards Texas. When one of these rings breaks off at the peak of hurricane season, it provides a source of heat energy capable of providing fuel for rapid intensification of any hurricanes that might cross over. The Loop Current is not predicted to shed an ring over the next month, as predicted by the latest 1-month forecast from the U.S. Navy. However, the last eddy broke off in July of 2009, ten month ago, and it is unusual for the Loop Current to go more than eleven months without shedding an eddy. I expect we'll see the Loop Current shed an eddy in July or August, just in time to pose the maximum threat for hurricane season. According to an interesting February 2004 article published by offshore-engineer.com, reliable forecasts of these currents and eddies are not available yet. Keep in mind that surface currents are largely driven by winds, and wind forecasts are not reliable out more than about 10 days.

Quoting kuppenskup:Here's a stupid question but I figured I would ask the experts:I live in South Florida. You know how Hurricanes suck up water from the ocean and then release? Well With the presence of this oil spill, if we had a Hurricane move in from the Gulf of Mexico would that mean there is a possibility of a Hurricane releasing the oil over land once the system moves inland? There's probably a simple answer but can anyone help me out on this one?

Here's a stupid question but I figured I would ask the experts:I live in South Florida. You know how Hurricanes suck up water from the ocean and then release? Well With the presence of this oil spill, if we had a Hurricane move in from the Gulf of Mexico would that mean there is a possibility of a Hurricane releasing the oil over land once the system moves inland? There's probably a simple answer but can anyone help me out on this one?

The shear map updated and still shows a pocket of very low shear where the convection is east of Florida (5-10 knots.)

Also to note that shear is lifting in the Southern Carribean, notice the 10-20 knots over 10 degrees N. I am starting to see how this Carribean system could form. I agree with some that it could be a make or break system to if it moves a bit north, it could be destroyed.

Quoting jeffs713:Actually... my neighbor works with both of the rigs that are drilling the relief wells to try and stop the leak. They actually have 2 rigs working 24/7 to intercept the bore done by the Deepwater Horizon, and stop the leak permanently. (they even made the two rigs work in competition, to speed it up even more) Does that work for military hours?

While I'm glad they have the full court press going, I hope the competitive nature of the relief well drilling does not introduce additional risk. I'm sure there is scads of oversight to prevent a relief well from becoming a second disaster, but the pressure of competition in addition to the already existing pressure to stop the leak may have an adverse, rather than a positive, effect on noticing and properly attending to "little" problems as they arise. I was not encouraged to hear that there was a competitive element present.

At 248 PM CDT... National Weather Service Doppler radar indicated acluster of strong thunderstorms near Metairie... or over the southend of The Causeway. The thunderstorms were nearly stationary.

The cluster of strong thunderstorms will affect areas in and aroundMetairie and New Orleans Lakeview area.

The primary threat from these storms is wind gusts to near 40 mph...which could down tree limbs and blow around unsecured small objects.Seek shelter in a safe home or building until these storms havepassed.

These storms could produce rainfall amounts of one to two inches in ashort period of time... resulting in ponding of water around low lyingroadways. Remember... do not drive your vehicle into water coveredroadways. The depth may be too great to allow a safe crossing.

The one that develops near or east of the Bahamas is the one east of Florida on the Euro. Nothing forming near Bermuda is going to end up near Florida. If a low moves near Bermuda it would be a baroclinic one taking off and phasing with the longwave trough to the north, leaving another piece behind near the Bahamas.

Quoting stormhank:is it possible that peice of snergy left behind in the vicinity of the bahamas could tack back towards florida as a tropical system? The shear is high in that region now isnt it?

If the trough-split piece gets blocked by the ridge over the NE US then yes it would retrograde westward towards Florida, which is shown on the Euro. Whether it develops or not will be worked out as the situation evolves. Wind shear is part of that, and due to the complexity of the situation we can't know for sure, but if the surface circulation becomes vertically stacked with the upper low, then wind shear won't be as much of a problem for it.

Quoting Levi32:It appears the 12z ECMWF wants to take a baroclinically-driven piece of energy out to the northeast into the waiting longwave trough, while leaving another piece behind with the trough-split tail piece to get stuck around the Bahamas underneath the blocking ridge to the north over the eastern US.

This could be the mess that the GFS is still trying to figure out. The Euro seems to have a good handle on taking the baroclinic low out but still leaving the cut-off piece behind, which makes a lot of sense. The GFS 12z is starting to figure it out by trying to leave a piece behind, unlike previous runs which took the whole thing out and phased it with the longwave trough. It still doesn't have as good a handle on it as the Euro though.

BP said Monday it hopes to siphon as much as half of the oil leaking into the Gulf of Mexico and is getting ready to shoot mud into a blown-out well later this week to try and stop all of it.

BP PLC chief operating officer Doug Suttles said at a press conference that the company will never again try to produce oil from the well, though BP did not rule out drilling elsewhere in the reservoir.

"The right thing to do is permanently plug this well, and that's what we will do," Suttles said.

Meanwhile, scientists said they were concerned about the ooze reaching a major ocean current that could carry it through the Florida Keys and up the East Coast. Suttles said a mile-long tube is funneling a little more than 42,000 gallons of crude a day from a blown-out well into a tanker ship.

Pressures look higher here than on previous runs and other models, including the Caribbean where the other weak low is. I think they will be a bit lower than this, but regardless you can see the possibilities with a trough-split getting stuck under a block to sit in this area for several days. At least subtropical mischief is definitely a possibility here.

It appears the 12z ECMWF wants to take a baroclinically-driven piece of energy out to the northeast into the waiting longwave trough, while leaving another piece behind with the trough-split tail piece to get stuck around the Bahamas underneath the blocking ridge to the north over the eastern US.

while the Raleigh site shows the low in the SW Caribbean, the other site barely even hints at it

The Raleigh site spaces the isobars 2mb apart, while the ECMWF site has them 5mb apart. The former is much better for viewing tropical features which show up better with smaller spacing. In the tropics it's hard to get a 5mb change in pressure unless it's associated with a large or powerful feature.